This invention relates to a paper feeding device for use in an image forming apparatus such as copying machine, facsimile machine.
There have been known an image forming apparatus provided with a paper feeding device including an inverting portion for inverting the copy paper sheet fed from a paper cassette and feeding the inverted sheet to a registration roller pair to reduce the size of apparatus.
There has been a paper feeding device having a circular guide member and an inverting roller provided in the circular guide member. However, such paper feeding device requires a driving portion and drive transmission for the inverting roller, which makes it impossible to reduce the size of apparatus.
Also, there has been known a paper feeding device having an inverting portion in which an outer guide member and an inner guide member, these member having a predetermined curved form, are opposed to each other at a specified space.
However, such conventional paper feeding devices are complicated in construction and thus have problems of feeding copy paper sheets improperly and involving jams. Specifically, the copy paper sheet ted From the paper cassette is likely to get entangled on Feeding rollers due to a bending of the leading end of copy paper sheet, causing a jam. Also, a jam is likely to occur in an inlet portion of the inverting portion. Further, the inverted copy paper sheets have on different positions the bending portion provided in the inverting process, resulting in often the problem that the registration roller pair fails to nip the leading end of copy paper sheet.
In addition, removing of jammed sheet is not easy. The inverted copy paper sheet has a resilient against to the inverting. This resilient causes a trailing end of the inverted copy paper sheet to hit a nearby member when the copy paper sheet leaves the paper cassette, consequently making nuisance noises.
Also, the conventional image forming apparatus is provided with a paper cassette having a paper push-up member made of a metal, involving in jams on the account of the metal push-up plate. Specifically, the metal paper push-up member is provided in a forward portion of a cassette casing of a resin material. One end of the metal paper push-up member is rotatably attached to the cassette casing while the other end is biased upwards by a spring. A leading end of a stack of copy paper sheets placed in the cassette casing is biased upward by the other end of the metal paper push-up member being biased upward. When the cassette carrying the stack of copy paper sheets is mounted on the apparatus, a top surface of the stack of copy paper sheets comes into pressing contact with the feeding roller by the upward biased push-up member. Being driven, the feeding roller feeds copy paper sheets sequentially from uppermost copy paper sheet.
In this feeding of copy paper sheets, however, electrostatic charges occurs on copy paper sheets due to friction between them to attract sheets to each other, involving multifeed. Further, such electrostatic attraction will occur in a downstream portion of the paper feeding device. The electrostatic charges cannot be grounded because the push-up member is made of metal but the cassette casing is made of resin. Accordingly, there has been the motivation of grounding the electrostatic charges on copy paper sheets placed in a paper cassette by a simpler construction.
It is an object of the present invention to provide a paper feeding device which has overcome the above-mentioned problems.
It is another object of the present invention to provide a paper feeding device which is compact and simple in construction, and can assuredly prevent jams.